Does the NBA preseason matter?

by Roland Beech, 82games.com

(revised to include 2007-08 season data)

Sure the preseason games matter to the players trying to make the team, the veterans trying to test out their bodies coming from injuries, and for the league itself perhaps to have some build up for the regular season tipoff. The question though is do the preseason records matter?

Is a team's won-lost mark in the exhibition games any indication or tip-off as to how the regular season will unfold? You hear announcers hand down their opinions, but I've yet to see any study on the matter...so let's examine the issue 82games style!

Tracking down preseason stats is no easy feat, but I've compiled a five year database for the 2001-02 season through 2007-08. That's not a huge sample, but a decent look for our purposes.

Correlations:
.35 Preseason win% --> Regular Season win%
.55 Last Year win% --> This year Regular Season win%
.31 Change in this preseason win% vs last preseason win% --> Change in this year wins vs last year wins

Now the confidence intervals on these are large due to an n=206, but still it's fair to say that a .35 correlation is reasonably healthy and suggests that yes the preseason records do have some significance in setting a tone for how things may go when the real games begin. The NBA does have more consistency from year to year than many sports, the NFL correlation from one year's record to the next for example was just .25 in one recent five year span.

Also, the fact that an improvement in preseason win % from one year to the next has a .31 correlation to a change in regular season wins is also notable.

BEST preseason records ('01-02 to '07-08)

Year

Team

Preseason

Regular Season

2002-03

Detroit

8-0

1.000

50-32

0.610

2004-05

Phoenix

7-1

0.875

62-20

0.756

2005-06

Denver

7-1

0.875

44-38

0.537

2003-04

Utah

7-1

0.875

42-40

0.512

2007-08

Atlanta

7-1

0.875

37-45

0.451

2003-04

Memphis

6-1

0.857

50-32

0.610

2004-05

Denver

6-1

0.857

49-33

0.598

2002-03

New Jersey

6-1

0.857

49-33

0.598

2006-07

Toronto

6-1

0.857

47-35

0.573

2007-08

Orlando

5-1

0.833

52-30

0.634

2001-02

Minnesota

5-1

0.833

50-32

0.610

2001-02

Toronto

5-1

0.833

42-40

0.512

2006-07

Golden State

5-1

0.833

42-40

0.512

2005-06

Dallas

6-2

0.750

60-22

0.732

2002-03

Sacramento

6-2

0.750

59-23

0.720

2005-06

Phoenix

6-2

0.750

54-28

0.659

2006-07

Chicago

6-2

0.750

49-33

0.598

2005-06

Memphis

6-2

0.750

49-33

0.598

2005-06

LA Clippers

6-2

0.750

47-35

0.573

2004-05

Memphis

6-2

0.750

45-37

0.549

2005-06

LA Lakers

6-2

0.750

45-37

0.549

2004-05

Philadelphia

6-2

0.750

43-39

0.524

2004-05

Cleveland

6-2

0.750

42-40

0.512

2007-08

Toronto

3-1

0.750

41-41

0.500

2006-07

Orlando

6-2

0.750

40-42

0.488

2003-04

Seattle

6-2

0.750

37-45

0.451

2007-08

Indiana

6-2

0.750

36-46

0.439

2005-06

Houston

6-2

0.750

34-48

0.415

Average

46-36

0.561

Average gain of 4 wins from coming season compared to last

WORST preseason records

Year

Team

Preseason

Regular Season

2004-05

Seattle

2-6

0.250

52-30

0.634

2004-05

Sacramento

2-6

0.250

50-32

0.610

2002-03

NO/Oklahoma City

2-6

0.250

47-35

0.573

2004-05

Boston

2-6

0.250

45-37

0.549

2003-04

New York

2-6

0.250

39-43

0.476

2001-02

Washington

2-6

0.250

37-45

0.451

2006-07

Charlotte

2-6

0.250

33-49

0.402

2003-04

Philadelphia

2-6

0.250

33-49

0.402

2006-07

Portland

2-6

0.250

32-50

0.390

2007-08

Charlotte

2-6

0.250

32-50

0.390

2003-04

Phoenix

2-6

0.250

29-53

0.354

2002-03

LA Clippers

2-6

0.250

27-55

0.329

2001-02

Denver

2-6

0.250

27-55

0.329

2003-04

Washington

2-6

0.250

25-57

0.305

2005-06

Portland

2-6

0.250

21-61

0.256

2007-08

Seattle

2-6

0.250

20-62

0.244

2005-06

San Antonio

2-7

0.222

63-19

0.768

2001-02

Cleveland

1-5

0.167

29-53

0.354

2006-07

Cleveland

1-6

0.143

50-32

0.610

2007-08

Cleveland

1-6

0.143

45-37

0.549

2001-02

Philadelphia

1-6

0.143

43-39

0.524

2004-05

Atlanta

1-6

0.143

13-69

0.159

2003-04

Orlando

1-7

0.125

21-61

0.256

2002-03

Denver

1-7

0.125

17-65

0.207

2007-08

Miami

0-7

0.000

15-67

0.183

Average

34-48

0.415

Average decline of 4.6 wins from coming season compared to last

So that's some pretty nice visual confirmation for preseason believers. Of course it might cross your mind that preseason records could vary in significance based on the prior year success of a team. After all a great team the previous year probably lets the mainstay guys ease through the exhibition games with minimal minutes while the team looking to improve might be running the regular season starters out there for big minutes.

Correlation of Preseason Record to Regular Season Record:
.59 Teams coming off a less than 30 win season
.40 Teams coming off a 30 to 39 win season
.46 Teams coming off a 40 to 49 win season
-.02 Teams coming off a 50+ win season

Aha! You say. That proves it then, great teams can ignore the preseason. Well, not entirely, since the sample sizes again get too small to really have conclusive value. Still it is suggestive of that theory, and more importantly perhaps it seems that for a poor prior year team, the preseason results really do have some bearing on whether improvement can be expected.

Teams with winning preseason records off a <30 win season

Year

Team

Preseason

Regular Season

Prior Yr

2004-05

Phoenix

7-1

0.875

62-20

0.756

29-53

2003-04

Memphis

6-1

0.857

50-32

0.610

28-54

2006-07

Toronto

6-1

0.857

47-35

0.573

27-55

2003-04

Miami

5-2

0.714

42-40

0.512

25-57

2006-07

New York

4-2

0.667

33-49

0.402

23-59

2003-04

Toronto

4-2

0.667

33-49

0.402

24-58

2007-08

Memphis

4-2

0.667

22-60

0.268

22-60

2003-04

Denver

5-3

0.625

43-39

0.524

17-65

2006-07

Atlanta

5-3

0.625

30-52

0.366

26-56

2007-08

Boston

4-3

0.571

66-16

0.805

24-58

2002-03

Houston

4-3

0.571

43-39

0.524

28-54

2004-05

Orlando

4-3

0.571

36-46

0.439

21-61

2003-04

Cleveland

4-3

0.571

35-47

0.427

17-65

To put it in perspective, the rare poor prior year team that strings together some wins in the preseason has seen an average gain of 17 wins in the next year!

Now if you extend it to look at any team <50 wins the prior year with a say .700 or better preseason it's a average gain of 7.5 wins.

All right, so which '07-08 teams have shown signs of life in '08-09 "meaningless" games?

6-2 Minnesota (22-60 last yr)

Are we destined to see some revival for the Timberwolves this coming season? Trying to project performance from the preseason alone is likely a foolish endeavor, but on the other hand if you're a fan of a team that's anything less than a rock solid 50+ win type, you might want to root for some exhibition wins after all.

One last oddity to wrap it up: teams that have improved their preseason win% over last year by .400 or more gain an average of 17 wins...this season that again tabs the Timberwolves, but also the Hornets who were .500 in '07-08 preseason but a perfect 1.000 this time out!

On the flip side, teams that lose .250 or more off their preseason win% have lost an average of almost six wins...this season Charlotte, Milwaukee, Sacramento, Memphis, Indiana, Toronto and Atlanta "could have done better" in the October classics.